JP2002199692A - Stepping motor, stepping motor device and its drive method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stepping motor structure, a stepping motor device and its drive method. SOLUTION: A permanent magnet 5 having a rotary polygon mirror 6 on a rotary shaft 1 and a plurality of poles whose magnetization state is in the form of a substantially sine wave in the inside is adhered to a rotor yoke 4 providing a notch part 8 on a part thereof and rotatably provided. A stator magnetic pole 2 performing a stator winding 3 in the inside of the permanent magnet 5 is fitted to a bearing holder 14 having a circular arc-like deformation prevention groove preventing caulking, when the polar number of the stator magnetic poles in made F, the polar number M of the permanent magnet 5 satisfies M=4F/3, the permanent magnet 5 is cylindrical, and intervals with the surface of the stator magnetic pole teeth have uniform size air gaps over one circumference. A leakage magnetic flux detector is provided on the face opposite to the notch part 8, and the stop of a rotor is detected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stepping motor structure for rotating a rotary polygon mirror for measuring a distance, a direction, and a relative speed of a preceding automobile, a stepping motor apparatus, and a driving method thereof.

[0002]

2. Description of the Related Art Conventionally, a printer, a high-speed fax,
In many cases, a stepping motor using a permanent magnet as a rotor is used for driving a rotating unit of an office machine such as a copying machine for PC because of high efficiency. In recent years, there has been an increasing interest in preventive safety technology for preventing traffic accidents by making cars intelligent. In realizing such preventive safety technologies, one of them is driving environment recognition,
There is an inter-vehicle distance control technology using a laser radar and an image recognition technology. The apparatus in this technique requires a laser scanner using the stepping motor and the rotating polygon mirror.

[0003] The above-mentioned stepping motors are mainly two-phase stepping motors for applications requiring medium accuracy, and have excellent cost performance for applications requiring high precision and low vibration and low noise. A phase stepper motor is used. As a stepping motor for office machines such as laser printers and facsimile machines that require low positioning unevenness and high positioning accuracy, a cylindrical permanent magnet rotor with a large number of cylindrical magnets or a large number of pole teeth A three-phase machine with a hybrid rotor in which a permanent magnet is sandwiched between two magnetic plates and a stator having pole teeth formed opposite to the rotor surface can provide high resolution and high torque. Many are adopted.

The stepping motor having the permanent magnet type rotor structure is step-driven precisely by one step angle by a driving pulse input from the outside, and the output shaft of the motor is rotated as if it is intermittently driven. In addition, the permanent magnet used for the rotor increases drive torque,
Rare earth magnets are increasingly used. Such a permanent magnet is alternately magnetized in the form of a strip in the circumferential direction, and the magnetic flux density on the surface of the magnet shows a substantially trapezoidal distribution when measured along the circumferential direction of the magnet. Furthermore, the magnetic pole teeth of the stator yoke often have a trapezoidal or triangular surface shape in order to obtain high torque.

[0005] A three-phase machine having a cylindrical permanent magnet type rotor or hybrid type rotor and a stator having pole teeth is
As described above, high torque can be obtained with high resolution. However, since the distribution of the surface magnetic flux density of the magnetized permanent magnet has a substantially trapezoidal shape along the circumferential direction, if the output torque is to be increased, a step-like drive is easily obtained,
Vibration at the time of trying to drive or stop the rotor is increased, and it becomes difficult to smoothly drive the rotor. In other words, noise and vibration are generated by the vibration torque component included in the torque generated by the product of the exciting current and the field magnetic flux density, so that the field magnetic flux density generated in the air gap between the permanent magnet and the stator of the rotor is The above structure including many harmonics increases noise and vibration.

Japanese Patent Application No. 05-221388 discloses a permanent magnet type stepping motor which solves the above problems, smoothes the rotation of the rotor, and reduces the damping of the rotor when starting or stopping the motor. And Japanese Patent Application No. 09-325197.

In Japanese Patent Application No. 05-221388, a permanent magnet of a rotor is skew-magnetized, and the magnetic flux distribution on the surface of the magnetized permanent magnet is made substantially sinusoidal along the circumferential direction. The shape of the magnetic pole teeth of the stator yoke was rectangular.

Japanese Patent Application No. 09-325197 discloses that the relationship between the number of stator poles Q and the logarithm N of the S and N poles of the rotor is Q = 6k, and N = yk (6n ± 1), and the stator magnetic poles were excited in a two-phase / three-phase excitation mode.

[0009]

The stepping motors disclosed in the above publications have the following problems. That is, in the device disclosed in Japanese Patent Application No. 05-221388, the magnetized state of the rotor is made substantially sinusoidal to reduce vibration and noise. Since each magnetic pole has a continuous cross-sectional shape with slight irregularities, it is difficult to manufacture because it is subjected to skew magnetization. Further, as for the number of poles of the rotor and the stator, it is disclosed that only appropriate number of magnetic poles (N-pole and S-pole) are skew-polarized, but the number is not mentioned.

In Japanese Patent Application No. 05-221388, the relationship between the number of stator poles and the logarithm of the rotor is determined so that the stator magnetic poles are excited in a two-phase / three-phase excitation mode. However, there is no mention of the magnetized state of the rotor.

In the stepping motor disclosed in each of the above publications, furthermore, when the load suddenly fluctuates on the rotating shaft and the rotation stops due to step-out, the stopped state is maintained. For this reason, if the resistance value of the winding is small without generating back electromotive force in the stator winding, an excessive current flows. Excessive inflow of current heats the windings, causing the temperature of the adhesive or other material that fixes the windings to rise, resulting in insulation failure, etc.
Failure may occur.

The present invention solves the above problem, and prevents a stepping motor having less vibration and a stepping motor from being restarted even when the rotation is stopped due to step-out due to a steep load fluctuation of a rotating shaft. An object of the present invention is to provide a stepping motor device and a driving method thereof.

[0013]

In order to achieve the above object, the present invention provides a stepping motor, comprising: a permanent magnet rotor having a plurality of poles fixed to a rotating shaft;
A stator having a stator magnetic pole having stator magnetic pole teeth in which exciting windings are wound in a star or delta connection with a plurality of magnetic poles, wherein the permanent magnet type rotor is alternately different in a circumferential direction. When the number of poles of the stator magnetic pole is F, the number of poles M of the permanent magnet type rotor satisfies M = 4F / 3, and the permanent magnet type rotor is The stator has a cylindrical shape that is rotatably disposed, and is disposed to face the stator magnetic pole tooth surface of the stator via an air gap of uniform dimensions over one circumference, The surface magnetic flux distribution has a substantially sinusoidal shape along the circumferential direction.

[0014] In the stepping motor according to the second aspect, the rotor is disposed opposite to the stator magnetic pole tooth surface with a uniform size air gap over the entire circumference between the rotor and the stator. A cylindrical bearing fixed to a rotatable shaft rotatably provided by a pair of bearings opposed to each other via a cylindrical bearing holder for fixing the rotatable shaft to a predetermined portion of the housing; Is characterized in that the bearing holder is set up by being caulked on a base on which the stepping motor is mounted.

According to a third aspect of the present invention, in the stepping motor, the bearing holder includes an arc-shaped deformation preventing groove for preventing deformation due to caulking.

According to a fourth aspect of the present invention, in the stepping motor, the arc-shaped deformation preventing groove of the bearing holder is provided along a circumference of an end in contact with a base on which the stepping motor is mounted.

According to a fifth aspect of the present invention, in the stepping motor, the permanent magnet rotor is provided opposite to the stator magnetic poles on a rotor yoke fixed to the rotating shaft, and the rotor yoke leaks magnetism of the rotor. And a leakage magnetic flux detector that detects leakage magnetic flux leaking from the rotor is provided at a position facing the notch.

According to a sixth aspect of the present invention, there is provided a stepping motor for detecting a magnetic pole change on a cylindrical end face of a cylindrical permanent magnet provided on a rotor yoke fixed to a rotating shaft so as to face a stator magnetic pole. And a leakage magnetic flux detector.

According to a seventh aspect of the present invention, the stepping motor is fixed to a rotary shaft rotatably provided via a cylindrical bearing holder provided upright on a base on which the stepping motor is mounted, and rotates together with the rotary shaft. A rotating polygon mirror that freely rotates is provided on an outer periphery of the rotor yoke so that a magnetic pole of a permanent magnet rotor of the stepping motor and each mirror surface of the rotating polygon mirror correspond to each other.

According to another aspect of the present invention, there is provided a stepping motor device comprising: a permanent magnet rotor having a plurality of poles fixed to a rotating shaft; and a stator having an exciting winding wound around the plurality of magnetic poles in a star or delta connection. A stator having magnetic pole teeth, and a rotating polygon mirror fixed to the rotating shaft and rotatably rotating with a rotating shaft in which a magnetic pole of the permanent magnet rotor and each mirror surface are arranged in correspondence with each other. Provided on the outer periphery of the rotor yoke, the permanent magnet rotor is magnetized alternately in the circumferential direction in different directions, and when the number of poles of the stator magnetic pole is F, the number of poles M of the permanent magnet rotor is M Satisfies M = 4F / 3, and the permanent magnet type rotor has a cylindrical shape in which the stator is rotatably arranged, and has a cylindrical shape with the stator magnetic pole tooth surface of the stator. Through an air gap of uniform dimensions The stepping motor has a surface magnetic flux distribution that is substantially sinusoidal along the circumferential direction, and detects a change in magnetic pole provided on the end face of the cylinder of the permanent magnet type rotor of the stepping motor. A three-phase 1-2 excitation type drive signal is applied to a leakage magnetic flux detector and three excitation power supply terminals in a star or delta connection wound around a plurality of magnetic poles of the stepping motor to rotate the stepping motor. It is characterized by comprising driving means for controlling and means for detecting the position of the rotary polygon mirror based on a signal from the leakage magnetic flux detector.

According to a ninth aspect of the present invention, there is provided a stepping motor device comprising: a permanent magnet type rotor having a plurality of poles fixed to a rotating shaft; and a stator having an exciting winding wound around the plurality of magnetic poles in a star or delta connection. And a stator having a stator magnetic pole having magnetic pole teeth, wherein the permanent magnet type rotor is magnetized alternately in different directions in the circumferential direction, and when the number of stator magnetic poles is F, The number of poles M of the permanent magnet type rotor is M = 4F
/ 3, the permanent magnet type rotor has a cylindrical shape in which the stator is rotatably arranged inside, and extends around the circumference of the stator magnetic pole tooth surface of the stator. And a stepping motor whose surface magnetic flux distribution is substantially sinusoidal along the circumferential direction, and wound around a plurality of magnetic poles of the stepping motor. A drive signal of a three-phase 1-2 excitation method is applied to three excitation power supply terminals in a star or delta connection, and a leakage magnetic flux detector for detecting a magnetic flux leaking from a notch provided in the rotor yoke. A drive means for controlling the rotation of the stepping motor by a signal and a means for repeating the processing of the rotation control a predetermined number of times and notifying a warning when the rotation does not reach a normal rotation are provided.

According to a tenth aspect of the present invention, in the stepping motor driving method, a permanent magnet rotor having a plurality of poles fixed to a rotating shaft, and an exciting winding wound around the plurality of magnetic poles in a star or delta connection. And a stator having a stator magnetic pole having stator magnetic pole teeth, wherein the permanent magnet type rotor is magnetized alternately in different directions in the circumferential direction, and the number of stator magnetic poles is F. Sometimes, the pole number M of the permanent magnet type rotor is M
= 4F / 3, and the permanent magnet type rotor has a cylindrical shape in which the stator is rotatably arranged inside, and has a circumference between the stator and the magnetic pole teeth surface of the stator. And a stepping motor whose surface magnetic flux distribution is substantially sinusoidal along the circumferential direction, and wound around a plurality of magnetic poles of the stepping motor. Magnetic flux leakage detecting means for applying a three-phase 1-2 excitation type drive signal to the three exciting power supply terminals having the star or delta connection and detecting a magnetic flux leaking from a notch provided in the rotor yoke. Drive means for controlling the rotation of the stepping motor in accordance with a signal from the motor. The drive means includes three exciting power supply terminals in a star or delta connection wound around a plurality of magnetic poles of the stepping motor. The stepping motor is driven by applying a driving signal of the phase 1-2 excitation method, a signal from the leakage magnetic flux detector is detected, and a signal change speed of the leakage magnetic flux detector 9 and a driving signal of the stepping motor are detected. Compare the signal with the signal, if there is a difference of more than a certain value in the comparison result, stop the supply of the drive signal, supply the drive signal again after a predetermined time, stop and supply the drive signal, It is characterized in that a predetermined number of repetitions is repeated, and an alarm is issued when normal rotation is not reached.

[0023]

FIG. 1 is a side sectional view of an embodiment of a stepping motor according to the present invention. The cylindrical rotating shaft 1 is rotatably provided on a cylindrical bearing holder 14 via bearings 12a and 12b. The bearing holder 14 is erected on the plate 11 by a method described later, and a spacer 16 is provided on the outer periphery of the bearing holder 14. A projection 101 is provided inside the bearing holder 14, and the upper bearing 1 is provided.
The spring 13 is compressed and inserted between the projection 101 and the lower bearing 12b. A ring 102 is provided below the rotating shaft 1 so as to prevent the bearing 12b from falling. The bearing 12b is held down by a repulsive force generated by the spring 13 being compressed and inserted between the spring 13 and the projection 101. , The rotating shaft 1 does not move up and down.

The spacer 16 has a structure described below.
For example, the stator magnetic pole 2 made of a laminated silicon steel plate or the like is fitted in the bearing holder 14 and the spacer 16
Is supported so that it does not fall downward. The stator magnetic pole 2 is provided with a stator winding 3 described later. The stator winding 3 is connected to the pin 15 and is pulled out to the outside by the connector 10 via a driver circuit and a drive circuit (not shown) provided on the printed circuit board 17, and a control (not shown) Microcomputer (MPU). The pins 15 connect a total of four, that is, a three-phase stator winding 3 and a neutral point of the stator winding 3 as described later.

The rotating shaft 1 is opposed to the stator magnetic pole 2.
A rotor yoke 4 made of a magnetic material and fitted to a bush 19 made of a non-magnetic material such as stainless steel fixedly mounted on the motor is rotatably provided. On the side of the rotor yoke 4 facing the stator magnetic pole 2, a permanent magnet 5 made of, for example, a rare earth magnet is provided over the entire circumference between the stator magnetic pole 2 and the rotor yoke 4. An air gap having a uniform size is provided between the stator magnetic pole teeth (not shown) provided in the apparatus. The rotor yoke 4 and the permanent magnet 5 are fixed with an adhesive or the like.

Since the magnetic pole teeth of the stator magnetic pole are provided along the circumference of the circle in a structure as will be described in detail with reference to FIG. The shape of the periphery of the permanent magnet 5 provided with is also circular. Therefore, the permanent magnet 5 has a cylindrical shape having a stator inside. The positional relationship between the rotor and the stator may be reversed. That is, the structure may be such that the permanent magnet 5 serving as the rotor is inside and the stator magnetic pole serving as the stator is outside.

The permanent magnet 5 magnetizes a cylindrical magnetic body alternately with different polarities in the circumferential direction, and its surface magnetic flux distribution has a substantially sinusoidal shape along the circumferential direction. Such magnetization, inside the cylindrical magnetic body, provided along the inside of the cylindrical magnetic body, arc-shaped, insert an electromagnet with windings applied to a predetermined number of magnetic poles, DC current flows and magnetizes.

The rotary polygon mirror 6 is provided on the upper part of the bush 19, and the rotary polygon mirror 6 is
Are fixed by fitting six metal fittings 7a and 7b (others not shown) provided on the upper part of the rotary shaft 1 into a ring 100. The rotary polygon mirror 6 is provided with a projection 110 for positioning with the bush 19, and is positioned between the rotary polygon mirror 6 and the rotor yoke 4 by fitting into a hole 111 provided in the bush 19. .

The positioning groove 22 is aligned with a positioning groove (not shown) provided in the permanent magnet 5 to position the permanent magnet 5 and the rotor yoke 4 so that the rotating polygon mirror 6, the rotor yoke 4 and the permanent magnet 5 are fixed. Positioning with the magnet 5 is performed.

A leakage magnetic flux detector 9b composed of a Hall element for detecting a magnetic flux leaking from the permanent magnet 5 is provided below the rotating portion of the permanent magnet 5, and the strength of the magnetic pole changes according to the rotation of the permanent magnet 5. Detect Since the positions of the rotating polygon mirror 6 and the permanent magnet 5 are determined as described above, the position of the rotating polygon mirror 6 can be known by detecting the output of the leakage magnetic flux detector 9b.

The printed board 17 is fixed to the plate 11 by bolts 18a and nuts 18b.

FIGS. 2A and 2B are views of the stepping motor according to the embodiment of the present invention as viewed from above in the embodiment of FIG. 1, wherein FIG. 2A is a top view, and FIG. a)
It is an enlarged view of the B section. In FIG. 2A, the rotary polygon mirror 6 has six mirrors, but may have a different number of surfaces. The rotating polygon mirror 6 includes a ring 100 provided on the rotating shaft 1 with six metal fittings 7a and 7b (the others are not shown) provided on the upper part of the rotating polygon mirror 6 described in FIG.
It is fixed by being fitted into six notches (not shown) provided on the upper part of the rotary polygon mirror 6.

The printed circuit board 17 has a driver circuit 21b
Are connected to the stator winding 3 by a printed wiring (not shown) in a manner described later. The driver circuit 21b is connected to the drive circuit 21a by a printed wiring (not shown), and the drive circuit 21a is connected to the connector 10 by a printed wiring (not shown).

The pins 15 for connecting the stator windings 3
a, 15b, 15c, and 15d, which are respectively connected to stator winding terminals U, V, and W, which will be described later, and a neutral point N of the stator winding. Each of the pins 15 is connected to the printed circuit board 17.
Are connected to the driver circuit 21b by a printed wiring (not shown). In addition, the neutral point N of the stator winding is connected to the pin 15d so that the connection portion of the neutral point N of the stator winding swings due to vibration or the like, and an accident such as disconnection or short circuit does not occur. Therefore, such pins are not connected to the driver circuit 21b.

At a position facing the permanent magnet 5, a leakage magnetic flux detector 9a is provided as described later.

In FIG. 2B, the positioning groove 22 is
By positioning the permanent magnet 5 and the rotor yoke 4 by aligning with the positioning groove 23 provided in the permanent magnet 5, the rotary polygon mirror 6, the rotor yoke 4, and the permanent magnet 5 are positioned.
Is performed.

FIG. 3 is a view for explaining the rotor yoke 4 of the stepping motor according to the present invention.
3A is a cross-sectional view in the PR direction, FIG. 3B is a top view, FIG.
(C) is a diagram viewed from a plane having the cutout portion 8 as viewed in the QK direction. A permanent magnet 5 is adhered to the inside of the rotor yoke 4, and a part of the rotor yoke 4 has one pole in the rotation direction of the permanent magnet 5 so that the magnetic flux of the permanent magnet 5 can be easily leaked. A notch 8 having a length of, for example, about 70%, which does not exceed the length, is provided. The number of the cutout portions 8 may be not one but plural, and the number of the leakage magnetic flux detectors 9a may be plural instead of one.

The notch 8 is provided at a position where the maximum magnetic flux density of a predetermined magnetic pole is reached. Such positioning is performed as follows. That is, when the positioning groove 22 is aligned with the positioning groove 23 provided in the permanent magnet 5, the positioning groove 22 and the positioning groove 22 are positioned so as to match the position where the maximum magnetic flux density at a predetermined pole of the permanent magnet 5 is reached. The relationship between the groove 23 and the notch 8 is defined.

FIG. 2 shows a position facing the notch 8.
The magnetic flux leakage detector 9a shown in FIG. The leakage magnetic flux detector 9a detects the leakage magnetic flux leaking from the permanent magnet 5, and functions as described later.

FIG. 4 is a view of the bearing holder 14, wherein FIG. 4 (a) is a bottom view as viewed from the direction B in FIG. 4 (b), and FIG. 4 (b) is a bearing in FIG. 4 (a). FIG. 4C is a partial cross-sectional view of the holder 14 when viewed from the direction A, and FIG. 4C is an enlarged view of a portion B in FIG. 4B. FIG. 4D is a view showing deformation of the caulking portion 44 when the caulking portion 44 is crimped when there is the caulking portion 44 described later, and FIG. FIG. 9 is a diagram showing deformation of the bottom of the bearing holder 14 when the bottom of the bearing holder 14 is swaged.

The bearing holder 14 has a cylindrical shape as shown in FIG. A projection 101 is provided inside the cylinder, and the bearing 12 b is fixed by the repulsion of the spring 13 by the projection 101.

As shown in FIG. 4B, a ring 100 for fixing six metal fittings provided at the upper part of the rotary polygon mirror 6 is provided at the upper part, and a constricted part 43 fitted to the plate 11 is provided at the lower part. Are provided on the outer circumference of the bearing holder 14 over the entire circumference. Further, a caulking portion 44 and an arc-shaped groove 42 for preventing deformation due to caulking are provided on the bottom of the bearing holder 14 over the entire circumference.

The bearing holder 14 is a plate 1
1 is inserted into a mounting hole (not shown) provided on the plate 1 and stands upright on the plate 11 and is fitted as follows.
That is, the bearing holder 14 inserted into the mounting hole (not shown) provided in the plate 11 is provided with the caulking portion 44 provided at the bottom in the direction of the arrow B in FIG. It is fitted to the plate 11 by applying pressure in the direction. The caulking part 44 to which pressure is applied
Is deformed to the outside 44 of the cylinder as shown in FIG.

The outwardly deformed portion 44 corresponds to the plate 11
The constricted portion 43 and the deformed portion 44b which fit with the plate 11 sandwich the plate 11, and the bearing holder 14 is fixed to the plate 11. Further, the inner side 45 of the cylinder is absorbed by the arc-shaped groove 42 for preventing deformation, and the distortion does not reach the inner side 45 of the bearing holder 14. In the case where there is no arc-shaped groove 42 for preventing deformation, the pressure obtained in the cylindrical direction of the bearing holder 14 leaves a caulking mark 421, and the inner side 45 of the bearing holder 14 is also distorted. )
Deform like. Such distortion and deformation reduce the strength of the bearing holder 14 and reduce the bearing holder 1.
The fitting force between the plate 4 and the plate 11 also decreases.

FIG. 5 is a diagram for explaining the relationship between the permanent magnet 5 and the stator magnetic pole 2. FIG.
FIG. 5B is a diagram showing a magnetized state of the permanent magnet 5.

In FIG. 5A, the number of poles of the permanent magnet 5 is 12 (the number of logarithms of N and S poles is 6), and the number of poles of the stator magnetic pole 2 is 9; Other values may be used as long as the relationship described below is satisfied between the magnet 5 and the stator magnetic pole 2.

The stator magnetic pole 2 has magnetic pole teeth 2aU, 2aV,
2aW and magnetic pole columns 2bU, 2bV, 2bW,
A stator winding (not shown) is wound around the magnetic pole columns 2bU, 2bV, and 2bW as described later. The surfaces of the magnetic pole teeth 2aU, 2aV, and 2aW facing the permanent magnet 5 are as follows:
An air gap having a uniform dimension is provided around the circumference of the surface of the stator magnetic pole 2 and the permanent magnet 5 over one circumference.

The magnetized state of the permanent magnet 5 of the rotor is shown in FIG.
As shown in (b), the surface magnetic flux distribution is magnetized so as to be substantially sinusoidal along the circumferential direction. That is, when the rotation of the permanent magnet 5 changes from the S pole to the N pole, as shown in FIG.

FIG. 6 is a block diagram of an embodiment of the stepping motor device according to the present invention. The stator winding terminals U, V, W of the stepping motor 60 are connected to output terminals UO, VO, WO of the three-phase driver circuit 21b, respectively. Inputs UIN, V of the three-phase driver circuit 21b
IN and WIN include output terminals C1 and C1 of the drive circuit 21a.
2, C3 are input terminals S1, S2, S of the drive circuit 21a.
3 is connected to output terminals CU, CV and CW of an MPU (microcomputer) 62 which is a driving means for controlling the rotation of the stepping motor 60. Also, MP
Outputs of the leakage magnetic flux detectors 9a and 9b formed of Hall elements are connected to input terminals CH and CQ of U62 by signal lines 63 and 6 respectively.
4 are connected to each other. Note that the driver circuit 21b, the drive circuit 21a, the MPU 62, and the power supply circuit of the leakage magnetic flux detector 9 are omitted. Also, a predetermined program (not shown) is stored in the MPU (microcomputer) 62, and executes processing of a stepping motor device as described later.

The drive circuit 21a switches each phase for exciting the stator winding by a predetermined pulse signal.
Drive circuit 21a from output terminals CU, CV, CW of U62
Output a signal for generating a signal of a three-phase 1-2 excitation system, which is a known method of driving a stepping motor. Further, although the stator windings 3U, 3V, and 3W of the stepping motor 60 are star-connected in FIG. 6, other connection methods such as delta connection may be used.

The stator windings 3U, 3V and 3W are respectively wound on the magnetic pole columns 2bU, 2bV and 2bW shown in FIG. 5 as follows. That is, the stator winding 3U has the same number of turns as the magnetic pole 2bU, the stator winding 3V has the same number of turns as the magnetic pole 2bV, and the stator winding 3W has the same number of turns as the magnetic pole 2bW. Magnetic pole teeth 2aU, 2aV, 2aW due to the magnetic flux of
And the permanent magnet 5 are wound uniformly so as to generate a predetermined magnetic pole, for example, an N pole on the surface facing the permanent magnet 5.

FIG. 7 is a diagram for explaining the relationship between the drive signal and the current when the stepping motor 60 is driven by the three-phase 1-2 excitation method. FIG. 7A shows the excitation signal in each step. 7 (b) is a drive signal signal at each step, and FIG. 7 (c) is the current I flowing through the stator windings 3U, 3V, 3W at each step.
It is a figure which shows the change of U, IV, and IW current, respectively. Here, the currents IU, IV, IW correspond to the stator windings 3U, 3V,
The current flowing from the terminals U, V, and W of 3W is positive, the current flowing out is negative, and the current flowing from the terminal is shown as one unit current in FIG. 7C.

When driving by the three-phase 1-2 excitation method, 6
A half cycle is completed in steps, and the result is as shown in FIG. As shown in FIG. 7A, when the stepping motor 60 is driven by the three-phase 1-2 excitation method, the stator windings 3U, 3V, and 3W of the stepping motor 60 include:
In each step, a one- or two-phase drive signal is alternately output from the driver circuit 21b. That is, as shown in FIG. 7B, in step 1, the drive signal is output only to the output terminal UO of the driver circuit 21b, and in step 2, the drive signal is output to the output terminals UO and VO of the driver circuit 21b. Then, in step 3, the drive signal is output only to the output terminal VO of the driver circuit 21b.

At the timing shown in FIG.
A drive signal as shown in FIG.
V, 3W, the currents IU, I
V and IW are as shown in FIG. That is, assuming that the impedance of each winding is equal to 2Z, the combined impedance between the terminals is 3Z regardless of what drive signal is applied to each terminal.

For example, in Step 1, when a drive signal is applied only to the stator winding 3U and the other winding terminals are grounded, a current IU flows from the terminal U to a winding having an impedance of 2Z, The current is shunted by 1/2 each to the stator windings 3V and 3W having an impedance of 2Z. In step 2, when drive signals are applied to the stator windings 3U and 3V, the stator windings 3U and 1 / 2V
Of the current flows into the stator winding 3W, merges with the stator winding 3W, becomes IW, and flows out of the terminal W. Similarly, the current of each winding in each step is as shown in FIG. As is clear from FIG. 7 (c), the current flowing through each winding is not a rectangular current for each phase, but a stepwise current, and a permanent magnet type rotor magnetized in a substantially sine wave shape. And the rotor is driven smoothly.

FIG. 8 is a diagram for explaining how the rotor rotates when the stator winding is excited by the three-phase 1-2 excitation type drive signal shown in FIG. FIG.
Each of FIGS. 8A to 8F corresponds to each step in FIG. In FIG. 8, the magnetic poles of the rotor are two poles of only the N pole and the S pole for simplification of description, and are not shown.

In FIG. 8A, in step 1, when a drive signal is applied only to the stator winding 3U, a current IU flows from the terminal U, and the magnetic pole N causes the stator windings 3V and 3W to flow. And so on. The S pole is generated so as to be in the direction of the stator winding 3U. Similarly, the magnetic pole S is generated by the current IW flowing out of the stator winding 3W so as to be in a direction between the stator windings 3U and 3V. Similarly, a magnetic pole N is generated by the current IV flowing out of the stator winding 3V, and a magnetic pole S is generated in a direction between the stator windings 3U and 3W. The combined magnetic fields of the S pole and the N pole generated by the respective windings are ST and NT, respectively, as illustrated.

Similarly, in step 2, when a drive signal is applied to the stator windings 3U and 3V, a current of 1/2 from the stator winding 3U and a current of 1/2 from the stator winding 3V flow. Then, it merges with the stator winding 3W, becomes IW, and flows out of the terminal W. With such a current, the S pole, N
The combined magnetic field of the poles is 6 to the right as shown in FIG.
After rotating 0 degrees, ST and NT are obtained. Similarly, the combined magnetic fields ST and NT rotate to the right by 60 degrees each and make one rotation in six steps, and the magnetic poles of the rotor make one rotation in six steps by being attracted by the rotating magnetic field generated by the stator windings. . However, FIG.
In FIGS. 8C to 8F, the composite magnetic field NT is not shown.

FIG. 9 shows the relationship between the rotating magnetic field when the stator winding is excited and the rotor for the embodiment of the present invention. (A) corresponds to each step. In FIG.
The number of magnetic poles U, V, and W of the stator 90 is 3 poles each, that is, 9 poles in total, and the number of magnetic poles of the rotor 91 is 12 poles. Then, a drive signal is applied to each winding (not shown) at the timing shown in FIG. 7A as shown in FIG. In such a case, the rotation angle per step is 1/12 as compared with FIG. 8, and the rotor 91 has three magnetic pole rotors, 36 in three steps.
One rotation smoothly in steps.

(Determining the number of poles) When the number of poles of the stator magnetic poles is F, the number of poles M of the permanent magnet type rotor is determined as follows. That is, when the stepping motor is driven in three phases, the number F of the stator magnetic poles is a multiple of three. Since the rotor is provided with a multi-pole rotating magnet having S and N poles, the rotor has a multiple of 2 of the number of pole pairs M / 2. Accordingly, there are various combinations with the number of poles F of the stator magnetic poles, where the number of poles F of the stator magnetic poles is a multiple of 3 and is a multiple of 2 of the number of pole pairs M / 2 of the permanent magnet type rotor. In the present invention,
The relationship between the number of poles M of the permanent magnet type rotor and the number of poles F of the stator magnetic poles should be such that M = 4F / 3 so that the rotation of the sine wave magnetized permanent magnet type rotor becomes smooth. To decide.

The operation of the stepping motor device of the present invention will be described below with reference to FIG. The drive circuit 21a
Three-phase 1-2, a well-known stepping motor driving method
An excitation type signal is generated, and a series of three-phase signals as shown in FIG. 7A are continuously output from output terminals C1, C2, and C3. The drive signal is applied to the input terminals WIN, VIN, and WIN of the driver circuit 21b. The drive circuit 21a and the driver circuit 21b can be realized by a known commercially available semiconductor integrated circuit or the like, and the drive signal applied to the input is converted into three-phase currents IU, IV, IW.
The MPU 62 generates a signal for operating the drive circuit 21a by a known method.

The three-phase currents IU, IV, IW are supplied from the terminals U, V, W of the stepping motor 60 to the stator winding 3.
U, 3V, and 3W, and the stepping motor 60 is rotated at a predetermined speed.

A method of driving the stepping motor device of the present invention, which operates as described above, will be described below. A leakage magnetic flux detector 9 a provided at a position facing the notch 8 provided in a part of the rotor yoke 4 detects a magnetic flux leaking from the permanent magnet 5 provided on the rotor yoke 4. When the stepping motor 60 rotates, a detection signal is obtained at the input terminal CH of the MPU 62 to which the output of the leakage magnetic flux detector 9a is connected, in synchronization with the rotation of the rotor yoke 4. Such a detection signal changes positive and negative due to leakage magnetic flux generated alternately by the N pole and the S pole of the permanent magnet 5.
Therefore, the MPU 62 detects the signal of the input terminal CH, and
If the detection signal changes positively or negatively at a predetermined speed, it can be known that the motor is rotating normally.

When the stepping motor 60 stops rotating due to some abnormality, for example, a sudden increase in load,
The output of the leakage magnetic flux detector 9a does not change between positive and negative, and the constant value or the change speed decreases. The MPU 62 compares the output change speed of the leakage magnetic flux detector 9a with a signal output to the drive circuit 21a for driving the stepping motor,
When there is a difference equal to or more than a certain value, the supply of the driving signal is stopped. After a predetermined time, the drive signal is supplied again. The MPU 62 repeats the supply of the drive signal a predetermined number of times. If the stepping motor 60 does not rotate normally, the MPU 62 notifies the lamp (not shown) and the system equipped with the stepping motor 60 of an abnormality. Notify.

The leakage magnetic flux detector 9b detects magnetic flux emitted from the lower part of the rotor yoke 4. The positional relationship between the rotor yoke 4 and the rotary polygon mirror 6 is determined as described above.
Therefore, the relative position of the rotary polygon mirror 6 can be known by detecting the change in the magnetic flux of the rotor yoke 4. M
The PU 62 inputs the output of the leakage magnetic flux detector 9b via a signal line 64, knows the position of the rotary polygon mirror 6, and measures the inter-vehicle distance, direction, and relative speed of a preceding vehicle (not shown). Output to the device.

Since the position of the rotating polygon mirror 6 at which the output of the leakage magnetic flux detector 9a changes is fixed, the absolute position of the rotating polygon mirror 6 can be determined by processing the output together with the output of the leakage magnetic flux detector 9b. You can know.

[0067]

According to the first aspect of the present invention, there is provided a permanent magnet type rotor having a plurality of poles fixed to a rotating shaft, and an exciting winding wound in a star or delta connection around a plurality of magnetic poles. And a stator having a stator magnetic pole having stator magnetic pole teeth, wherein the permanent magnet type rotor is magnetized alternately in a circumferential direction in different directions, and the number of stator magnetic poles is F and Then, the pole number M of the permanent magnet type rotor is M = 4
F / 3, the permanent magnet type rotor has a cylindrical shape in which the stator is rotatably arranged,
The stator is arranged opposite to the stator magnetic pole tooth surface with an air gap of uniform dimensions over one circumference, and its surface magnetic flux distribution is substantially sinusoidal along the circumferential direction. As a result, a stepping motor that rotates smoothly can be realized. Further, in the conventional stepping motor, a magnetic material such as iron is further provided on the magnetized magnetic material so that the magnetic flux distribution after the magnetization is close to a rectangular shape so that the magnetic flux becomes uniform. It is. However, in the present invention, a magnetic material such as iron for uniforming the magnetic flux is not provided, and the magnetic flux is magnetized in a substantially sinusoidal shape along the circumferential direction, so that the permanent magnet type rotation is achieved. The structure of the child could be simplified.

According to the stepping motor of the second aspect, the rotor is disposed outside the stator so as to face the stator magnetic pole tooth surface via an air gap of uniform dimensions over the entire circumference. At the same time, the rotary shaft is fixed to a rotatable shaft rotatably provided by a pair of bearings opposed to each other via a cylindrical bearing holder for fixing the rotary shaft to a predetermined portion of the housing, and fixes the rotary shaft. Since the cylindrical bearing holder is provided upright on the base on which the stepping motor is mounted, the stepping motor can be mounted on the base with a simple structure.

According to the third aspect of the present invention, since the bearing holder has the arc-shaped deformation preventing groove for preventing deformation due to caulking, the motor after the stepping motor is mounted on the base can be removed from the base. It was possible to prevent poor mounting that would otherwise occur.

According to the stepping motor of the fourth aspect, the arc-shaped deformation preventing groove of the bearing holder is provided along the circumference of the end on the side in contact with the base on which the stepping motor is mounted. It is possible to prevent a mounting failure in which the motor is detached from the base due to an external force from each direction of the motor after the motor is mounted on the base.

According to the stepping motor of the fifth aspect, the permanent magnet rotor is provided on the rotor yoke fixed to the rotating shaft so as to face the stator magnetic poles, and the rotor yoke is provided on the rotor yoke. Notch for leaking, and a leakage magnetic flux detector for detecting leakage magnetic flux leaking from the rotor at a position facing the notch, providing a stepping motor having a steep load change. Stop can now be detected.

According to the stepping motor of the sixth aspect, the magnetic pole is provided on the cylindrical end face of the cylindrical permanent magnet provided on the rotor yoke fixed to the rotating shaft so as to face the stator magnetic pole. By providing a leakage magnetic flux detector for detecting a change, the position of the magnetic pole of the permanent magnet can be detected.

According to the seventh aspect of the present invention, the stepping motor is fixed to a rotatable rotary shaft via a cylindrical bearing holder provided upright on a base on which the stepping motor is mounted. A rotating polygon mirror that is rotatably rotated together with the outer circumference of the rotor yoke, with the magnetic poles of the permanent magnet rotor of the stepping motor and the mirror faces of the rotating polygon mirror corresponding to each other. An inexpensive device for measuring distance, direction, and relative speed was realized.

According to the stepping motor device of the eighth aspect, the permanent magnet type rotor having a plurality of poles fixed to the rotating shaft and the exciting winding wound around the plurality of magnetic poles in a star or delta connection. A stator having a stator magnetic pole having stator magnetic pole teeth, and a rotating polygon mirror fixed to the rotating shaft and rotatably rotating together with a rotating shaft in which a magnetic pole of a permanent magnet rotor and each mirror surface are arranged in correspondence with each other. Is provided on the outer periphery of the rotor yoke, and the permanent magnet type rotor is magnetized alternately in different directions in the circumferential direction, and when the number of poles of the stator magnetic poles is F, the poles of the permanent magnet type rotor are The number M satisfies M = 4F / 3, and the permanent magnet type rotor has a cylindrical shape in which the stator is rotatably arranged, and has a stator magnetic pole tooth surface of the stator. Air gap of uniform size over one circumference between The surface magnetic flux distribution is substantially sinusoidal along the circumferential direction, and the magnetic pole change provided on the end face of the cylinder of the permanent magnet type rotor of the stepping motor. A leakage magnetic flux detector for detecting a magnetic field, and a drive signal of a three-phase 1-2 excitation system applied to three excitation power supply terminals in a star or delta connection wound around a plurality of magnetic poles of the stepping motor. A device for measuring the inter-vehicle distance, direction, and relative speed of a preceding vehicle by including a driving unit for performing rotation control of the vehicle and a unit for detecting a position of the rotary polygon mirror based on a signal from the leakage magnetic flux detector. Was realized at low cost.

According to the stepping motor device of the ninth aspect, the permanent magnet type rotor having a plurality of poles fixed to the rotating shaft, and the exciting winding wound around the plurality of magnetic poles in a star or delta connection. And a stator having a stator magnetic pole having stator magnetic pole teeth, wherein the permanent magnet type rotor is magnetized alternately in different directions in the circumferential direction, and the number of stator magnetic poles is F. Sometimes, the number of poles M of a permanent magnet type rotor is M =
4F / 3, the permanent magnet type rotor has a cylindrical shape in which the stator is rotatably arranged, and has a circumference between the stator magnetic pole tooth surface of the stator and the stator. The stepped motor is disposed opposite to each other with an air gap having a uniform size over the entire surface, and its surface magnetic flux distribution is wound around a stepping motor having a substantially sinusoidal shape along the circumferential direction, and a plurality of magnetic poles of the stepping motor. A drive signal of a three-phase 1-2 excitation method is applied to three excitation power supply terminals by star or delta connection, and a leakage magnetic flux detector that detects a magnetic flux leaking from a notch provided in the rotor yoke. Driving means for controlling the rotation of the stepping motor by the signal of, the process of the rotation control is repeated a predetermined number of times,
By providing a means for notifying a warning when the rotation does not reach the normal rotation, the stop of the stepping motor due to a sudden load change can be detected, and the motor can be prevented from being damaged.

According to a tenth aspect of the present invention, there is provided a permanent magnet type rotor having a plurality of poles fixed to a rotating shaft, and an exciting winding wound on a plurality of magnetic poles in a star or delta connection. And a stator having a stator magnetic pole having stator magnetic pole teeth, wherein the permanent magnet type rotor is magnetized alternately in different directions in the circumferential direction, and the number of stator magnetic poles is F. And the number of poles of the permanent magnet type rotor is M
Satisfies M = 4F / 3, and the permanent magnet type rotor has
The stator has a cylindrical shape in which the stator is rotatably arranged, and is opposed to a stator magnetic pole tooth surface of the stator via an air gap of uniform dimensions over one circumference. The surface magnetic flux is distributed to a stepping motor having a substantially sinusoidal shape along the circumferential direction and three exciting power supply terminals of star or delta connection wound around a plurality of magnetic poles of the stepping motor. Drive means for applying a drive signal of the phase 1-2 excitation method and controlling the rotation of the stepping motor by a signal from a leakage magnetic flux detector for detecting magnetic flux leaking from a notch provided in the rotor yoke; And applying a three-phase 1-2 excitation type drive signal to three exciting power supply terminals in a star or delta connection wound around a plurality of magnetic poles of the stepping motor. A stepping motor is driven to detect a signal from the leakage magnetic flux detector, and a signal change speed of the leakage magnetic flux detector 9 is compared with a drive signal signal of the stepping motor. If there is, stop supplying the drive signal, supply the drive signal again after a predetermined time, repeat the process of stopping and supplying the drive signal a predetermined number of times, and issue an alarm when normal rotation is not reached By doing so, the reliability of the device for measuring the inter-vehicle distance, direction, and relative speed of the vehicle could be improved.

[Brief description of the drawings]

FIG. 1 is a side sectional view of an embodiment of a stepping motor according to the present invention.

FIG. 2 is a diagram of the embodiment of FIG. 1 in the stepping motor of the present invention when viewed from above,
2A is a top view, and FIG. 2B is an enlarged view of a portion B in FIG. 2A.

3 (a) is a cross-sectional view in the PR direction, FIG. 3 (b) is a top view, and FIG. 3 (c) is a QK direction. FIG. 5 is a view as seen from a surface having a cutout portion 8 as viewed from above.

4A and 4B are views of a bearing holder, wherein FIG. 4A is a bottom view as viewed from a direction B in FIG. 4B, and FIG.
FIG. 4A is a partial cross-sectional view when viewed from the direction A, FIG.
4C is an enlarged view of a portion B in FIG. 4B, FIG. 4D is a diagram showing deformation of the caulked portion when there is a caulked portion, and FIG. It is a figure showing a deformation.

5A and 5B are diagrams illustrating a relationship between a permanent magnet and a stator magnetic pole, where FIG. 5A shows an arrangement of the permanent magnet and a stator magnetic pole, and FIG. It is a figure showing a state.

FIG. 6 is a block diagram of an embodiment of a stepping motor device according to the present invention.

7A and 7B are diagrams illustrating a relationship between a drive signal and a current when a stepping motor is driven by a three-phase 1-2 excitation method, and FIG. 7A illustrates a relationship between excitation signals in each step. FIG. 7 (b) is a drive signal signal in each step, and FIG. 7 (c) is a change diagram of a current flowing through the stator winding in each step.

FIG. 8 is a diagram for explaining how the rotor rotates when excited by the drive signal shown in FIG. 7; FIGS. It is a figure corresponding to each step in FIG.

FIG. 9 illustrates the relationship between the rotating magnetic field when the stator winding of the stepping motor according to the present invention is excited and the rotor. FIG. 9 shows the aforementioned FIG. 7 (a).
It is a figure corresponding to each step of.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rotating axis 2 Stator magnetic pole 3 Stator winding 4 Rotor yoke 5 Permanent magnet 9 Leakage magnetic flux detector 14 Bearing holder 21a Drive circuit 21b Driver circuit 60 Stepping motor 62 Microcomputer 3U, 3V, 3W Stator winding

 ──────────────────────────────────────────────────続 き Continued on front page F term (reference) 5H580 AA05 AA06 AA07 BB06 CA02 CA12 CB04 FA14 FC01 HH09 HH39 JJ09 5H605 BB05 BB14 BB19 CC03 CC04 CC10 DD03 EA02 EA16 EA19 EB10 EB37 EB38 GG03 GG04

Claims (10)

[Claims] 1. A permanent magnet type rotor having a plurality of poles fixed to a rotating shaft, a stator magnetic pole having stator magnetic pole teeth in which an exciting winding is wound around a plurality of magnetic poles in a star or delta connection. A permanent magnet rotor,
When magnetizing is performed alternately in different directions in the circumferential direction and the number of poles of the stator magnetic pole is F, the number of poles M of the permanent magnet type rotor is
M = 4F / 3, the permanent magnet type rotor has a cylindrical shape in which the stator is rotatably arranged, and has a stator magnetic pole tooth surface between the stator and the stator. A stepping motor, which is disposed to face each other via an air gap having a uniform size over one circumference, and has a surface magnetic flux distribution having a substantially sinusoidal shape along a circumferential direction. 2. In the stepping motor, the rotor is disposed outside the stator and opposed to the stator magnetic pole tooth surface with an air gap having a uniform size over the entire circumference. A cylindrical bearing fixed to a rotatable shaft rotatably provided by a pair of bearings opposed to each other via a cylindrical bearing holder for fixing the rotatable shaft at a predetermined position, and fixing the rotatable shaft. 2. The holder according to claim 1, wherein the holder is provided upright on a base on which the stepping motor is mounted.
4. The stepping motor according to claim 1. 3. The stepping motor according to claim 1, wherein the bearing holder is provided with an arc-shaped deformation preventing groove for preventing deformation due to caulking.
4. The stepping motor according to claim 1. 4. The stepping motor according to claim 1, wherein the arc-shaped deformation preventing groove of the bearing holder is provided along the circumference of the end on the side in contact with the base on which the stepping motor is mounted. 4. The stepping motor according to any one of claims 1 to 3. 5. In the stepping motor, the permanent magnet rotor is provided on a rotor yoke fixed to a rotating shaft so as to face a stator magnetic pole, and the rotor yoke leaks magnetism of the rotor. A leakage magnetic flux detector that detects leakage magnetic flux leaking from the rotor at a position facing the notch, the leakage magnetic flux detector being provided at a position facing the notch. The stepping motor as described. 6. A stepping motor for detecting a change in magnetic pole on a cylindrical end face of a cylindrical permanent magnet provided in a cylindrical shape opposite to a stator magnetic pole on a rotor yoke fixed to a rotating shaft. 6. The stepping motor according to claim 1, further comprising a magnetic flux detector. 7. The stepping motor is fixed to a rotating shaft rotatably provided via a cylindrical bearing holder provided upright on a base on which the stepping motor is mounted, and is rotatable with the rotating shaft. 2. The rotating polygon mirror that rotates is provided on the outer periphery of the rotor yoke so that a magnetic pole of a permanent magnet rotor of the stepping motor and each mirror surface of the rotation polygon mirror correspond to each other.
7. The stepping motor according to any one of claims 1 to 6. 8. A permanent magnet type rotor having a plurality of poles fixed to a rotating shaft, and a stator magnetic pole having stator magnetic pole teeth in which exciting windings are wound around the plurality of magnetic poles in a star or delta connection. And a rotating polygon mirror fixed to the rotating shaft and rotatably rotating together with a rotating shaft arranged in correspondence with the magnetic poles of the permanent magnet rotor and each mirror surface, provided on the outer periphery of the rotor yoke, The permanent magnet type rotor is magnetized alternately in different directions in the circumferential direction, and the number of stator magnetic poles is changed to F.
, The number of poles M of the permanent magnet type rotor is M = 4F /
3, the permanent magnet type rotor has a cylindrical shape in which the stator is rotatably disposed inside, and extends around the circumference of the stator magnetic pole tooth surface of the stator. A stepping motor whose surface magnetic flux distribution is substantially sinusoidal along the circumferential direction, and a cylinder of the permanent magnet type rotor of the stepping motor, which are arranged to face each other with an air gap having uniform dimensions. A leakage magnetic flux detector provided on an end face for detecting a change in magnetic poles, and a three-phase 1-2 excitation type drive to three exciting power supply terminals by star or delta connection wound around a plurality of magnetic poles of the stepping motor. A driving means for applying a signal to control the rotation of the stepping motor; and a means for detecting a position of the rotary polygon mirror based on a signal from the leakage magnetic flux detector. Apparatus. 9. A permanent magnet rotor having a plurality of poles fixed to a rotating shaft, and a stator magnetic pole having stator magnetic pole teeth in which excitation windings are wound around the plurality of magnetic poles in a star or delta connection. A permanent magnet rotor,
When magnetizing is performed alternately in different directions in the circumferential direction and the number of poles of the stator magnetic pole is F, the number of poles M of the permanent magnet type rotor is
M = 4F / 3, the permanent magnet type rotor has a cylindrical shape in which the stator is rotatably arranged, and has a stator magnetic pole tooth surface between the stator and the stator. A stepping motor whose surface magnetic flux distribution has a substantially sinusoidal shape along the circumferential direction and is arranged around a plurality of magnetic poles of the stepping motor is disposed so as to face each other with an air gap of uniform dimensions over one circumference. Leakage magnetic flux detection for applying a three-phase 1-2 excitation type drive signal to the three excitation power supply terminals by the rotated star or delta connection and detecting magnetic flux leaking from a cutout provided in the rotor yoke. A driving unit for controlling the rotation of the stepping motor by a signal from the device, and repeating the rotation control process a predetermined number of times,
Means for notifying an alarm when normal rotation is not reached. 10. A permanent magnet type rotor having a plurality of poles fixed to a rotating shaft, and a stator magnetic pole having stator magnetic pole teeth in which exciting windings are wound around a plurality of magnetic poles in a star or delta connection. Wherein the permanent magnet type rotor is magnetized alternately in the circumferential direction in different directions, and when the number of poles of the stator magnetic poles is F, the number of poles of the permanent magnet type rotor is M
Satisfies M = 4F / 3, and the permanent magnet type rotor has
The stator has a cylindrical shape in which the stator is rotatably arranged, and is disposed to face the stator magnetic pole tooth surface of the stator via an air gap of uniform size over one circumference. The surface magnetic flux is distributed to a stepping motor having a substantially sinusoidal shape along the circumferential direction and three exciting power supply terminals of star or delta connection wound around a plurality of magnetic poles of the stepping motor. Drive means for applying a drive signal of the phase 1-2 excitation method and controlling the rotation of the stepping motor by a signal from a leakage magnetic flux detector for detecting magnetic flux leaking from a notch provided in the rotor yoke; And applying a three-phase 1-2 excitation type drive signal to three exciting power supply terminals in a star or delta connection wound around a plurality of magnetic poles of the stepping motor. A stepping motor is driven to detect a signal from the leakage magnetic flux detector, and a signal change speed of the leakage magnetic flux detector 9 is compared with a drive signal signal of the stepping motor. If there is, stop supplying the drive signal, supply the drive signal again after a predetermined time, repeat the process of stopping and supplying the drive signal a predetermined number of times, and issue an alarm when normal rotation is not reached A stepping motor driving method.